1. Field of the Invention
This invention relates generally to a device for obtaining a sample of material from within a larger body of the material and more particularly, though not exclusively, concerns a soft tissue biopsy device for surgical use.
During the course of medical treatment it is sometimes necessary for a Doctor, Surgeon, or other qualified medical practitioner to obtain a sample of flesh or other soft tissue from a patient for further diagnostic analysis prior to the patient being treated. The need for a soft tissue sample may arise, for example, when a patient has a suspected tumour, the biopsy analysis identifying whether the tumour is benign or malignant, since this will dictate the most suitable course of treatment.
2. Description of the Related Art
FIG. 1 shows a perspective view of a section through a previously available soft tissue biopsy device generally indicated at 10. The device comprises a main body 12, a plunger 14, a sheath needle 16 and a sampling needle 18. The sampling needle 18 is secured to the plunger 14 and is arranged to pass through the outer sheath needle 16 which is secured to the main body 12. The main body 12 and the plunger 14 are commonly made from a plastics material, and the sheath needle 16 and the sampling needle 18 are made from surgical steel.
The device 10 is supplied in the condition shown in FIG. 1. In this condition the end of the sampling needle 18 is shrouded by the sheath needle 16. Prior to use the surgeon presses the plunger 14 into the main body 12 so that a flange 20 on the plunger 14 passes over an end stop 22 on the main body 12 and continues until it reaches the end face 24. Pressing the plunger 14 into the main body 12 in this way projects the sampling needle 18 forward out of the sheath needle 16. The device 10 is then driven into the patient so that the sampling needle 18 first punctures the soft tissue to be sampled followed by the sheath needle 16.
FIG. 2 shows a detail view of the end of the sheath needle 16 and the sampling needle 18. In FIG. 2(a) the sampling needle 18 is shown projecting from the sheath needle 16, and in FIG. 2(b) the sampling needle is shown, along with a soft tissue sample 28 retained in a sample collecting slot 26, retracted into the sheath needle 16.
Once the sampling needle and sheath needle have been inserted into the patient, the sampling needle is drawn back into the sheath needle. As the end of the sheath needle passes over the sample collecting slot 26 a soft tissue sample 28 is cut from the patient and retained in the sample collecting slot 26 by the sheath needle 16. To achieve this action, the plunger 18 is drawn back out of the main body until it reaches a stop position where the flange 20 contacts the end stop 22. The sampling needle is thus retracted into the sheath needle 16 along with the soft tissue sample 28 and the device is then removed from the patient prior to retrieval of the sample 28 from the sampling needle 18.
A problem with this arrangement, which the present invention aims to solve, is that manipulation of the sampling device 10 requires the use of at least two hands if the sample is to be successfully retrieved with minimum distress and injury to the patient. The surgeon must first carefully drive the sampling needle 18 and sheath needle 16 into the patient whilst pressing the plunger 14 down into the main body 12. Next, the surgeon must steady the main body and sheath needle with one hand whilst the plunger is drawn back out of the main body to the stop position with the other hand. Finally, as the device is pulled out of the patient, the skin surface surrounding the puncture must be supported to prevent it from becoming distended and causing unnecessary further pain or damage whilst at the same time the plunger must be retained in the stop position to ensure the sample is not lost.
Thus, an undue amount of dexterity is required of the surgeon during what should be a very simple and straightforward procedure. As a result it is not uncommon for an accident to occur. For example, if the surgeon inadvertently fails to retain the plunger in the stop position during the removal of the device from the patient, the sampling needle can slide back out of the sheath needle so that the tissue sample is lost. In the event that the sample is lost, the procedure must be repeated causing undue distress and injury to the patient and additional cost since a new sterile device will have to be used.